Four civilians and two policemen were killed Monday in roadside bombings in southern Afghanistan, officials said. "A car hit a roadside bomb this morning in Marja district of Helmand province, in which four civilians were killed and two others injured," the provincial police department said. Two policemen were killed and one injured when their vehicle struck a roadside bomb in the adjacent Uruzgan province, police spokesman Farid Ayel said. "The incident took place in the outskirts of Trinkot city, the provincial capital," Ayel was quoted as saying by DPA. At least 868 Afghan civilians were killed in 2012 by roadside bombs, a United Nations report said last week.